Structure and Inhibition of the SARS Coronavirus Envelope Protein Ion Channel

Pervushin, Konstantin; Tan, Edward; Parthasarathy, Krupakar; Lin, Xin; Jiang, Feng Li; Yu, Dejie; Vararattanavech, Ardcharaporn; Soong, Tuck Wah; Liu, Ding Xiang; Torres, Jaume

Isotopically labeled amino acids were derivatized with 9fluorenyl-methyloxycarbonyl (FMOC) [59] . The ETM peptide, corresponding to the transmembrane domain of SARS-CoV E (residues 8-38), E 8 TGTLIVNSVLLFLAFVVFLLVTLAIL-TALR-NH 2 , was synthesized using standard solid phase FMOC chemistry (Intavis Respep peptide synthesizer). The peptide was cleaved from the resin with trifluoroacetic acid (TFA). The lyophilized peptide was purified by HPLC, as described previously [21] . Lyophilization was performed in the presence of HCl (at the molar ratio of 20:1, HCl:peptide) in order to avoid formation of peptide-TFA adducts; consequently, the TFA band at ,1685 cm 21 was absent in the infrared amide I region (not shown). Peptide purity was further confirmed by electrospray ionization (ESI) mass spectrometry. During ETM synthesis, 15 Nlabeled amino acids were introduced at positions A22, V24, V25, and 13 C, 15 N-labeled amino acids at positions L18, L19 and L21.